Silver halide color light-sensitive materials give high-quality images and are used in many fields.
The demand for color, hard copies of information on images, which is converted into electric signals, is increasing with the development of image devices for office automation, the advent of the electron steal camera, the popularization of video and facsimile machines, the development of computer graphics and image sensor, and the advance of the digital processing technique of original images.
Conventional color light-sensitive materials generally have spectral sensitivity to blue, green and red colors. Generally, color CRTs (cathode ray tubes) are used to obtain images on such color light-sensitive materials from information on images, which have been converted into electric signals. However, the CRT is unsuitable for producing large-size prints.
Light-emitting diodes (LED) or semiconductor lasers are being developed as optical write heads capable of producing large-size prints. However, an optical write head which efficiently emits blue light has not yet been developed.
For example, when a light-emitting diode is used, color light-sensitive materials having three layers spectral-sensitized (to near infrared, red and yellow colors, respectively) must be exposed to a light source composed of a near infrared (800 nm) light-emitting diode, a red (670 nm) light-emitting diode and a yellow (570 nm) light-emitting diode. Such systems for recording an image are described in Nikkei New Material, pages 47 to 57 (Sep. 14, 1987) and are of partial practical use.
A system for recording an image on light-sensitive materials having three light-sensitive layers having spectral sensitivity to individual wavelengths by exposure to a light source composed of three semiconductor lasers [emitting light (880 nm), light (820 nm) and light (760 nm)] is disclosed in JP-A-61-137149 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
However, color light-sensitive materials which comprise, for example, three layers of blue-sensitive, green-sensitive and red-sensitive layers conventionally used for these systems, cannot be used to reproduce an image by an optical write head such as a light-emitting diode or a semiconductor laser. Color light-sensitive materials having three light-sensitive layers spectrally sensitized to near infrared, red and yellow colors cannot be used to photograph scenery or to record visible light such as that of a conventional color CRT. Accordingly, the use thereof is limited to the reproduction of an image by separate light sources.
Further, conventional light-sensitive materials require processing solutions and a long processing time. Hence, when image is rapidly outputted from information on an image, heat-developing color light-sensitive materials are superior. Many types of heat-developing light-sensitive materials are known.
For example, methods wherein dye images are formed by a coupling reaction of couplers with the oxidation products of developing agents are described in U.S. Pat. Nos. 3,761,270 and 4,021,240. However, the methods require complicated treatments such as the removal of silver due to the formation of a color image, nor are they simple processes. Further, color reproduction deteriorates when the silver is not removed.
A method wherein a positive dye image is formed by a silver dye bleaching process is described in U.S. Pat. No. 4,235,957. This method requires complicated processing stages, since the bleaching of the dye image with silver image is carried out.
Recently, methods have been proposed wherein a diffusible dye is imagewise transferred to a dye-fixing element by heat development, (i.e. transfer type heat developable color light-sensitive materials).
In these methods, a negative dye image as well as a positive dye image can be obtained by changing the type of dye-providing compounds to be used. These methods are described in more detail in U.S. Pat. Nos. 4,500,626, 4,503,137 and 4,559,290, JP-A-58-149046, JP-A-60-133449, JP-A-59-218443, JP-A-61-238056, EP-A-220746, Kokai Giho 87-6199 and EP-A-210660. These methods will be illustrated in more detail hereinafter.
In the light-sensitive materials described in these patent specifications, the spectral sensitization of the light-sensitive silver halide of each layer has only one light-sensitivity. Namely, the light-sensitive materials are designed so that they have three respective spectral-sensitized layers to blue, green and red colors for prints from a color negative and they have three respective spectral-sensitized layers to yellow, red and near infrared colors for an LED. Accordingly, these light-sensitive materials can be used only for the reproduction of an image by using separate light sources.